Major Breakthrough In The Mechanism Of Myelin Formation

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Major Breakthrough In The Mechanism Of Myelin Formation

http://www.medicalnewstoday.com/medicalnews.php?newsid=55770

The group of Dr. Michel Cayouette, researcher at Institut de

recherches cliniques de Montreal (IRCM), and Dr. Jonah Chan,

collaborator at the University of Southern California, will publish

in the next issue of the prestigious scientific journal Science, the

results of their study that could have a major impact on the

treatment of diseases such as multiple sclerosis, and peripheral

neuropathies.

At a basic level, our nervous system is like a collection of wires

that transmit electrical signals encoding our thoughts, feelings,

and actions, both conscious and unconscious. The connections in our

brain are formed by neurons that extend to each other and to muscles

long wires called axons. Just as an electrical wire needs

insulation, our axons require an insulating sheath (myelin) that

helps to propagate the electrical signal and maximize the efficiency

and velocity of these signals in our brain and body. It is this

property (myelination) that facilitates the long-distance

communication in our nervous system across junctions called

synapses, such that a thought can result in the movement of a finger

or a toe. Diseases and injury that compromise the integrity of

myelin such as multiple sclerosis, or peripheral neuropathies, have

dramatic consequences like paralysis, uncoordinated movements, and

neuropathic pain. The discovery reported in this study sheds light

on the mechanisms that control how myelin is formed during

development of the nerves. The article, which will be published in

the November 3rd issue of Science, constitutes an important step

forward in our understanding of the process of myelination, and

opens the way to new research in this field.

More specifically, the study showed that a protein called Par-3 is

at the base of the myelination process. This protein becomes

localized to one side of the myelin-forming cells called Schwann

cell, upon contact with the axon that is to be myelinated. Par-3

acts as a sort of molecular scaffold to set-up an " organizing

centre " , which brings together key proteins essential for

myelination, in particular a receptor for a molecule secreted by the

neurons. The scientists found that when they disrupted this

organizing centre, cells could not form myelin normally.

Importantly, their discovery demonstrates that Schwann cells need to

become polarized so that they know which side of the cell is in

contact with the axon so that they can initiate wrapping and bring

essential molecules to this critical interface. These studies open

the way to new research, which should help to identify other

components that are recruited at the organizing centre set-up by Par-

3. Importantly, in conditions such as multiple sclerosis or after

injury, it is believed that Schwann cells could be used to re-

myelinate axons. But so far this approach has proved to be

relatively inefficient. Therefore, these experiments bring about the

possibility that manipulating the Par-3 pathway in Schwann cells

might allow for more efficient re-myelination of damaged or diseased

nerves.